Insulated conductor and method of making same



July 20, 1937. s. J. ROSCH ET AL INSULATED CONDUCTOR AND METHOD MAKINGSAME Filed April 21, 1954 4 Sheets-Sheet l INVENTORS SAMUEL (.[lQQFC HV/ro FD/LuJr/ea P401. IKE/92L W IL ATTORNEYS July 20, 1937. 5. J. RoscHET AL 2,087,303

INSULATED CONDUCTOR AND METHOD OF MAKING SAME Filed April 21, 1934 4Sheets-Sheet 2 )(W'i' m) 4" v "If! INVENTORS SAMUEL J BOSCH ATTORNEYSJuly 20, 1937.

INSULATED Filed Apr S. J. ROSCH ET AL CONDUCTOR AND METHOD OF MAKINGSAME 4 Sheets-Sheet 3 BY PAUL fiffo 65/85 INVENTORs JAMuEL LI Eos CH V7TO FD/LUJTEO. I

ATTORNEYS July 20, 1931. J, ROSCH E; AL 2,037,303

INSULATED CONDUCTOR AND METHOD OF MAKING SAME Filed April 21, 1934 4Sheets-Sheet 4 INVENTORJ SAMUEL J50; CH

7770 FD/L (/J'TEO, BY .PAULMEO 65B 5 v ATTORNEYJ Patented July 20, 1937UNITED STATES PATENT OFFICE INSULATED CONDUCTOR AND*METHOD OF MAKINGSAME Delaware Application April 21, 1934, Serial No. 721,656

18 Claims.

This invention relates to electric conductors and particularly to anovel form of insulated cov ering therefor and the method of applyingsuch covering to a conductor. A characteristic feature relatesparticularly to the use of fluffy fibrous material, such as crude orcarded cotton, sisal, jute, asbestos, or otherfiuffy carded or uncarded,or relatively crude fibrous material having little or no inherenttensile strength but pro- 19 vided with a reinforcing member helicallyembracing the exterior thereof.

Heretofore, it has been suggested to build up fibres around a centralfilamentary supporting thread, such thread extending substantiallyaxially of the fibres. Such an interior thread or reinforcement islocated in the center of the mass of fibres and obviously does notembrace them and will not serve to prevent the outermost fibres of thebody from tending to fiuif outwardly. An

20 other suggestion in the prior art is the application oflongitudinally extending filamentary threads, which are adhesivelysecured to the fibrous mass.

A further old idea has been to build up the fibres about an adhesivelycoated longitudinal supporting thread by rolling or advancing the fibresabout the thread. In applying such 01d fibrous materials, it hasheretofore been suggested to mat them about the conductor by wrappingabout the insulated conductor, thus formed,

one or more twines or threads in various angles or directions, suchthreads, however, being on the outside of the assemblage including theconductor and the fibrous mass.

5 While loose fibrous materials have heretofore been applied to orincorporated in the insulating structure of electric conductors, ourinvention differs from the teachings of the prior art in materialrespects and novel and unobvious advantages are secured by incorporatingour novel features, as will be apparent from the following disclosure.One important aspect of the present invention over the interiorcentrally located or exteriorly longitudinally extending reinforcedfibres heretofore used is that our exterior helical reinforcement exertsa, confining action on the fibres. Moreover, the exterior spiral orhelical arrangement of our reinforcement endows the silver, roving, orloose spun yarn, or other fibrous material with a greater over-alltensile strength than would be the case with the straight longitudinalinterior or exterior reinforcements heretofore used. This is because thereinforcement, which we employ, in the nature of a coarse pitched helixaround the loose fibres, can stand a greater extent of pull withoutbreaking for a given size of reinforcing thread in view of the fact thatpart of the lengthwise pulling component of the force applied isresolved more or less into a constricting or compressing force on therelatively loose fiufly fibres.

Hence, there is less tendency for our improved reinforcement to break.Thus, the reinforced fibrous mass which we employ can Withstand muchgreater elongation without rupturing or disintegrating than can the oldfibrous slivers or masses of the prior art, in which the reinforcementsextend longitudinally either interiorly or exteriorly of the mass.

Our outer helical reinforcement also acts to prevent part of the fibrousmass from forming a fluffy accumulation, which would eventually latercause the member to break, when applied to the conductor by the servingmachine or other instrumentality used.

The use of the outer helical reinforcement about the loose fibres isimportant also in the method of applying the relatively loose fibrousmaterial to the conductor. In applying slivers or roving, of necessity acertain amount of tension is exerted on the work. The use of our ex"ternal and helically reinforced fibrous mass en ables us to apply thesame by the use of existing mechanism without making drastic alterationsthereto. During the application of the fibrous mass to the conductor,the helical reinforcing thread keeps the fluffy fibres within properbounds and when tension is applied to the reinforced mass the helicalthread exerts a constricting action on the fibres. reinforcement alsoenables us to impregnate the loose fibrous mass prior to its applicationto the conductor by passage through a liquid bath. The exteriorembracing reinforcement contributes materially to the success of suchimpregnation by preventing the loose wet or saturated fibres frompulling apart. Thus, the presence of this exterior helical reinforcementperforms important functions differing from the functions performed bythe reinforcements of the prior art.

In short, the constricting action of our outer spiral reinforcementgives rise to three important, novel and unobvious advantages, namely,it

increases the ability of the fibres to withstand tensile strain, it matsdown and holds the loose fibres within such restricted confines thatthey will not fluff outwardly to an extent which would interfere withthe operations or steps required to apply the fibrous mass to theconductor, and it Our novel helical makes it practical to impregnate thefibrous mass prior to its application to the conductor.

The above and other features of the invention will be apparent from thefollowing detailed description when read in connection with theaccompanying drawings and will be defined with particularity in theappended claims.

In the drawings- Fig. 1 is an enlarged view of a sliver or body offibres reinforced in accordance with our invention; Fig, 2 is a similar;view illustrating a short length of reinforced slubber roving; Fig. 3may be regarded as illustrative of a mass of fibres such as a sliver,roving or the like with an exterior reinforcement of flat fibrous tapesuch as paper or a narrow relatively thin limp textile material; Fig. 4is an enlarged view of a conductor having an insulated coveringembodying our invention, parts being broken away in the interest ofclearness; Figs. 5, 6, 7, 8 and 9 illustrate various modifiedembodiments of the invention; Fig. 10 is a diagrammatic viewillustrating a step in the method of applying the helical reinforcementto loose fibres; Fig. 11 is a somewhat diagrammatic view illustratingcertain steps in the method of applying reinforced fibres to aconductor; Figs. 12 and 13 illustrate modifications of certain steps inthe method of carrying out the invention.

Referring in detail to the drawings, Figs. 1 to 9 inclusive illustrateconductors having coverings in which the fibrous mass embodying ourinvention forms an important element.

In Fig. 1, A represents an elongated body or mass of loose fibres, suchas cotton, jute, asbestos, sisal or the like. This loose or fiuffy mass,in our invention, is surrounded by one or more helical reinforcements,such as indicated at B. These reinforcements may all be of the sameinclination or may have one or more reinforcements progressing helicallyin one direction around the mass and another reinforcement B progressingin the opposite direction around the mass. In short, we may employeither a single right hand helix or a right hand and a left handreinforcing helical body.

The mass of fibres illustrated at A in Fig. 1 may be regarded either asa sliver or roving of carded fibres or as a piece of ribbon lap, suchribbon lap differing from a sliver or roving in size and degree ofcoarseness of the fibres by the reason of two or more slivers beingsuperposed on each other. Or, the body of loose fibres A may be regardedas a length of material formed by longitudinally slitting a wide blanketor web of picker lap. Such picker lap differs from sliver or roving inthat it is uncarded and is a more crude product having been freed of itsmajor impurities.

Instead of using relatively crude material, such as those referred to,we may use amass of fibres, which have had a slight twist impartedthereto, such as a mass known as a slubber roving. Such slubber rovingis indicated at A in Fig. 2. This will carry our improved outer helicalreinforcement, indicated at B.

In the alternative feature illustrated in Fig. 3, I have shown a mass offibrous material A surrounded by an outer helical reinforcement B, whichmay be regarded as a relatively narrow strip of paper, or textilefabric, such as cambric or the like.

For convenience of description, the mass of fibrous material will behereinafter referred to as a sliver. But, it is to be understood thatthis term applies to either a crude or carded fibrous mass, such asproduced from ribbon lap, picker lap, or other processed or unprocessedfibres. In all cases, the mass of fibres will be reinforced by one ormore helical members, as above indicated.

Fig. 4 illustrates an embodiment of the invention wherein the conductorC is wrapped with a sliver A. This sliver may have been previouslyimpregnated with an insulating or water-proofing material or the slivermay first'be wrapped about the conductor and then the same passedthrough a bath. Over the covering thus provided, there may be an outerjacket, such as indicated at E, in the form of a braid of cotton or thelike. The helical reinforcement B embracing the sliver greatlyfacilitates the application of the silver to the conductor, as willappear hereinafter in the description of the method of applying the sameto the conductor.

Fig. 5 illustrates an embodiment of our invention, wherein the conductorC is provided with two layers of slivers, one layer being indicated bythe letter F and the other by the letter G. Over the layers of theseslivers, there may be applied a fibrous tape, such as indicated at H andover this there will be a braided or other outer jacket J. The layers Fand G formed of reinforced slivers may be saturated with suitableinsulating or weather-proofing compounds and the wrapping of tape H willserve as a barrier or dam to prevent the escape of an insulatingcompound, due for example to the heating of the conductor.

In the embodiment of the invention shown in Fig. 6, the conductor C isfirst wrapped with a layer of helically reinforced slivers A and overthis there is provided a jacket K, formed of similar helical reinforcedslivers A, which are interbraided with thread-like strands L. Thisjacket K is thus formed of the relatively bulky reinforced fibrousstrands A and the fine threadlike strands L, which cross the slivers AOver the jacket K, we provide a wrapping of fibrous tape M, which inthis instance may be perforated and the assemblage is enclosed in anouter braided jacket J of conventional form. The constructionillustrated in Fig. 7 is substantially the same as that illustrated inFig. 6, except that the tape M is omitted. The corresponding parts areidentified by reference characters similar to those used in Fig. 6.

Instead of wrapping the reinforced sliver or slivers around theconductor G, we may, as indicated in Fig. 8, provide one or more layersof reinforced slivers A, which extend longitudinally of the conductor Gand over such longitudinal reinforced slivers, we will provide awrapping of tape, such as indicated at H and over this there will be aconventional jacket J.

A further alternative is illustrated in Fig. 9, wherein a plurality ofhelically reinforced slivers A surround the conductor G and over thesethere is a layer of helically wrapped slivers A, which are enclosed by aconventional braid J.

Referring now to our improved method, we provide a suitable length orsliver of fibrous material such as fiuify cotton, asbestos fibres,sisal, or jute fibres, or combinations of the same, or any type ofloosely formed fibres or fibrous material, which are capable ofreinforcement by prespiralling or helically winding one or morereinforcing threads around such fibres. Fig. 10 diagrammatically showsthe step for reinforcing the fibres. In this figure, the fibrousmaterial coming from the doifer roll 0 of a carding machine may be ledthrough a trumpet or former P, so as to form a sliver or roving A. Asthe silver leaves the trumpet, the reinforcement B is applied to theexterior thereof. For this purpose, we have conventionally illustrated aflier Q carrying a cop or spool R. of reinforcing thread. Theapplication of the reinforcing thread in this manner serves to increasethe tensile strength of the sliver or roving to such an extent that thefibres thereof will not disintegrate or pull apart when tension isapplied. The helical reinforcement thus applied greatly facilitates theapplication of the sliver or roving to the exterior of the cable.

e sliver or roving is then wound on suitable spools, bobbins or cops.Such cops, as indicated at S in Fig. 11, are mounted on a flier S, whichis rotated by suitable mechanism so as to wrap the reinforced sliver orroving about the conductor C. The flier S may thus apply the wrappingsuch as indicated at F in Fig. 5. The thus wrapped conductor willprogress through another flier S carrying cops or bobbins S constitutingsupplies for a similar reinforced sliver which will apply the secondwrapping, such as indicated at G in Fig. 5. This second wrapping may bewrapped in a direction opposite to the first wrapping. The thus wrappedconductor will then pass through a suitable tank T carrying a liquidimpregnating compound, indicated at T. After passage through theimpregnating tank, the wrapped and impregnated conductor will have paperor fibrous tape H applied thereto, such tape being fed from tape supplyreels U carried by a taping head U. After the application of the tape,the thus covered conductor will pass through the center of the flier Vof a braiding machine carrying a plurality of cops V of suitable threadfor forming the braid on the wrapped and taped conductor.

Prior to the first wrapping of the reinforced sliver about the conductorC, the latter, if desired, may be passed through a tank W carrying anadhesive, in which case the first wrapping of slivers would beadhesively united to the conductor.

Instead of applying the impregnating compound to the reinforced sliversby passage through a tank T, as above described, we also contemplatesaturating the slivers before wrapping them around the conductor andsuch presaturating or loose fibrous material will be permissible in viewof the fact that the sliver is reinforced by the exterior helical memberand thus the wetted fibres will not pull apart and disintegrate underthe influence or the tension exerted during the operation of winding orwrapping them about the conductor.

We have illustrated the tape H wrapped helically around the reinforcedsliver wrappings. But, we also contemplate, in some cases, folding orapplying such paper or similar tape longitudinally about the insulatedconductor.

The method of producing a conductor, such as illustrated in Figs. 6 and'7, will differ from that described in connection with Fig. 11, in thatsome of the fliers on the braiding machine will carry bobbins or cops ofreinforced relatively bulky slivers and other cops or bobbins ofrelatively thinner threads, so that the braiding operation willinterweave the slivers A with the threads L. The thus formed braid maybe impregnated by passage through the tank carrying suitable insulatingor weather-proofing compounds, as will be understood.

In some cases, instead of forming the insulation braid of relativelybulky reinforced slivers, such as A with the thinner threads L, as inFigs. 6 and 7, we also contemplate forming the insulated covering as abraid, in which all component crossing strands are in the form ofslivers, each embraced by an outer helical reinforcing thread. such asindicated at B. The presence of such an outer reinforcing thread B,which has been prespiraled about the fluffy fibrous sliver, makes itpractical to handle such sliver in conventional braiding machines,because the reinforced sliver can be passed through or around the usualmetal guides of a braiding machine. And in a braiding operation, becauseof the presence of the prespiraled exterior reinforcing thread B, thefibres will not fluff out to an extent to jamb in the guides and theywill not pull apart. The exterior helical disposition of this threadaround the exterior of the sliver is of importance because when thesilver is bent around the guides in different directions on the braidingmachine the exterior thread largely takes the strain occasioned by thebraiding operation. The interiorly or straight exterior reinforcedslivers heretofore used could not be successfully handled onconventional types of braiding machine, insofar as we are aware, becausethey would not permit of bending around the guides in differentdirections, or the fiuiling out of such old slivers would cause theirbreakage due to sticking in the guides.

Instead of feeding the conductor vertically, and applying the reinforcedsliver by the I use of known types of braiding machines, in which thecarriers have been adapted for the operation, we may employ a spinninghead such as illustrated diagrammatically in Fig. 12, this head, inicated at X, carrying a plurality of spools or cops S When this type ofmechanism is used, the wrapping of tape may be applied by means of aplanetary taping head, indicated diagrammatically at U carrying aplurality of tape supply reels U The conductor thus wrapped may beadvanced through the machine by the usuai draw-off capstan Y and thematerial accumulated on a take-up reel Y. Or, instead of using thespinning head of the character shown in Fig. 12, the reinforced sliversmay be applied by a conventional type of stranding machine, such asdiagrammatically shown in Fig. 3, this stranding machine carrying aplurality of supply reels S the material being fed therefrom through thesuitable guides, in much the same manner the strands are fed through acabling machine to the core member of the cab-1e.

While we have described quite specifically cer tain conductors embodyingthe invention and various definite steps and sequences of steps inapplying the reinforced sliver to the conductor, it is to be understoodthat the drawings and the detailed description are to be interpreted inan iilustrative rather than a limiting sense since various modificationsand substitutions of equivalents may be made by those skilled in the artwithout departing from the invention as defined in the appended claims.

What we claim is:-

1. in the manufacture of insulated conductors, the method whichcomprises providing an elongated mass of loosely associated fibres oflow inherent tensile strength, applying a helical thread-likereinforcement about the exterior thereof and enclosing a conductor witha covering composed of such exteriorly pre-reinforced fibrous mass.

2. In the manufacture of insulated conduc tors, the method whichcomprises providing a sliver applying an exterior helical. reinforcementabout the exterior thereof and covering a conductor with suchpre-reinforced sliver.

3. Ii'i' the manufacture of insulated conductors, the method whichcomprises providing a. relatively bulky sliver of fibrous material andapplying a thread-like helical exterior reinforcetfient thereto,interweaving such reinforced sliver with relatively less bulkythread-like members about a conductor.

4. In the manufacture of insulated conductors, the method whichcomprises providing an elongated mass of loosely associated fibres oflow inherent tensile strength, applying a helical thread-likereinforcement about the exterior thereof, impregnating the thuspre-reinforced mass and then applying it to the conductor.

5. In the manufacture of insulated conductors, the method whichcomprises providing an elongated mass of loosely associated fibres oflow inherent tensile strength, applying a helical thread-likereinforcement about the exterior thereof, feeding such pro-reinforcedmass through a bath of impregnating material and applying the thusimpregnated mass to a conductor.

6. In the manufacture of insulated conductors, the method whichcomprises providing a plurality of relatively bulky elongated masses offibrous material and before assembling the masses with the conductorapplying a helical exterior reinforcement to each of said masses,interweaving such pro-reinforced masses with relatively less bulkythread-like members about a conductor and impregnating the coveredconductor thus formed.

7. In the manufacture of insulated conductors, the method whichcomprises providing a plurality of relatively bulky elongated masses offibrous material and before assembling the masses with the conductorapplying a helical exterior threadlike reinforcement around each mass,interweaving such pre-reinforced masses with relatively less bulkythread-like members about a conductor and impregnating the coveredconductor thus formed, applying a tape thereover and enclosing theassemblage in an outer jacket.

8. In the manufacture of insulated conductors, the method whichcomprises carding a fibrous material and forming a sliver therefrom,before assembling the latter with the conductor applying a helicalthread-like reinforcement about the exterior thereof and enclosing aconductor with a cover-ing composed of such exteriorly reinforcedsliver.

9. In the manufacture of insulated conductors, the method whichcomprises carding fibrous material and forming a sliver therefrom,before assembling the latter with the conductor applying a coarsepitched helical reinforcement about the exterior thereof, and wrappingsuch exteriorly reinforced sliver about a conductor.

10. In the manufacture of insulated conductors, the method whichcomprises carding fibrous material and forming a sliver therefrom,before assembling the latter with the conductor applying an exteriorhelical reinforcing thread thereto, applying a plurality oflongitudinally extending pieces of such reinforced sliver lengthwise ofa conductor and applying an outer covering to secure them to theconductor.

11. An electric conductor surrounded by a covering including anelongated mass of fibres constituting a sliver and reinforced by anouter member, which progresses helically around the exterior surface ofthe sliver.

12. An electric conductor surrounded by a covering including a sliverwhich is embraced by a reinforcing thread, which progresses helicallyaround the exterior surface of the silver.

13. An electric conductor surrounded by a covering including a pluralityof convolutions of a sliver each of which carries an outer helicalreinforcement.

14. An electric conductor surrounded by a covering including a pluralityof convolutions of a sliver which carries an outer reinforcing threadwhich progresses helically around the exterior thereof for augmentingthe tensile strength of the fibres of said sliver.

15. An electric conductor surrounded by a covering including a pluralityof longitudinally extending slivers, each embraced by an individualexterior helical reinforcement thread and an outer jacket enclosing suchslivers.

16. An electric conductor surrounded by a covering including a sliverwhich is embraced by an individual helical reinforcing thread, saidsliver being impregnated with an insulating material, an outer jacketand a wrapping of tape between the jacket and said sliver covering.

17. An electric conductor surrounded by a covering comprising arelatively bulky sliver having an individual outer helical reinforcingthread and being interwoven with a much less bulky thread.

18. An electric conductor having a plurality of longitudinally extendingslivers covering an exterior thereof, each of said slivers having anindividual outer helical thread-like reinforcement, and a wrapping ofsimilarly reinforced slivers around said longitudinally extendingslivers and an outer jacket enveloping the assemblage.

SAMUEL J. ROSCH. VI-TO F. or LUSTRO. PAUL M. ROGERS.

